In a medium bowl sift together the flour, salt and ¼ cup sugar 3 times.
In a large bowl with hand beaters or the bowl of a stand mixer with the whisk attachment beat the egg whites, lemon juice and vanilla on medium speed until soft peaks form.
Gradually add one cup of sugar (a little at a time), continue beating until stiff peaks form (don't over beat).
With a spatula fold in the flour mixture (a quarter cup at a time), gently fold until combined (do not over fold). Spoon into an ungreased 9 inch tube pan (angel food cake pan). Gently cut through the batter with a metal knife to eliminate any air bubbles.
Bake for approximately 40-45 minutes, or until toothpick comes out clean. Cool the cake upside down in the pan.
Remove from the pan (you will need to carefully run your knife around the edges to help release the cake) slice the cake in two layers, spread half the topping on one layer, add some berries, top with second layer and spread with remaining topping and berries or desired fruit. Enjoy!
FOR THE TOPPING
In a medium bowl beat together the cream, mascarpone and icing sugar (be sure to sift the icing sugar into the bowl to eliminate any lumps), beat until thick.
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Notes
To make homemade cake/pastry flour - For every cup of all purpose flour, remove two tablespoons and replace with two tablespoons of corn starch. Be sure to sift the flour and cornstarch together a couple of times, this way it is sure to be properly combined and lump free.I filled this cake with a whipped cream and mascarpone filling and of course some fresh fruit. You could also fill it with a lemon curd filling, a simple Chantilly Cream filling, which is whipping cream whipped with a little sugar and a teaspoon of vanilla extract. Or you could cut slices and top with fresh fruit and whipped cream. Or of course your favorite filling.Be sure to store the cake in an air tight container or wrap tightly and store in an airtight bag. It will keep up to two days at room temperature or one week in the fridge.To freeze the cake, wrap it tightly with foil or plastic wrap, and place it in a freezer bag or place the cooled cake in an airtight container. Properly stored, it keep for up to four to six months.